Spinal cord ischemia results in life-changing paralysis and paraparesis after major vascular, spine and spinal cord surgery, and spine trauma. Methods currently employed to detect spinal cord ischemia are based upon electrophysiology, monitoring the effect of ischemia upon electrical signal transmission. Degradation of these signals requires ionic gradients to fail, and cell death to begin. The current technology is therefore indirect and temporally delayed. It has also been proven to lack the specificity and reliability desired to avert such a devastating consequence as paralysis or paraparesis. We have developed a prototypical fiber optic device, based on Diffuse Correlation Spectroscopy (DCS) and Diffuse Optical Spectroscopy (DOS) principles, that permits rapid detection and continuous monitoring of changes in spinal cord blood flow and oxygenation. This novel device is an important step forward for neurophysiological monitoring, offering a new level of accuracy and immediacy for intraoperative detection of spinal cord ischemia and in the neurocritical care setting. This device may one day enable continuous, bedside, user friendly monitoring for spinal cord ischemia by anesthesiologists, neurointensivists, emergency, and nursing personnel. Specific Aims: Aim 1) To design and produce a second generation multi-level spinal cord fiber-optic probe, capable of axially discriminating ischemic disturbances across multiple vertebral regions in the spinal cord. Aim 2) To continue to develop and optimize a real-time fiber optic monitoring platform for the monitoring of spinal cord blood flow and oxygenation. Aim 3) To conduct preliminary bench and pre-clinical testing of the second generation multi- level probes and PXI-platform real-time monitor. Aim 4) To design and produce a compact, portable, user friendly, DCS/DOS monitor, capable of being used at the bedside. Aim 5) To complete bench and pre-clinical testing of the second generation probes and monitor.